(rec.audio.misc) Intended to be a catch-all for any any all posts that might not fit into one of the existing audio groups.
Basically, anything that is audio-related and doesn't belong somewhere
else is fair game.

(rec.audio.tech) A place for users to post concerning home consumer audio that are of a factual, practical, or theoretical
nature. Sample topics might include: "How do I compute standing wave frequencies?" or "Ported vs. non-ported speaker designs"

(rec.audio.pro) A forum for the discussion of professional audio products, recording and studio engineering as it relates to any
of following:- radio/tv audio for on-air and production, sound reinforcement &
recording.